Multiplex telegraph system employing electronic distributor



T. A. HANSEN Sept. 2, 1952 MULTIPLEX TELEGRAPH SYSTEM EMPLOYING ELECTRONIC DISTRIBUTOR Filed May 28, 1945 8 Sheets-Sheet 2 F I G.

F l G.

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FIG. 2

m 5 m R H B 0 N M A R E E m WW o 6 E w H T 1 J6 8 3 M 2 l J M 7 9 6 2 l i? w. v 3 m. m m 7 7 I 3 w m Sept. 2, 1952 T. A. HANSEN 2,609,452

MULTIPLEX TELEGRAPH SYSTEM EMPLOYING ELECTRONIC DISTRIBUTOR Filed May 28, 1945 8 Sheets-Sheet 3 STANDARD FREQUENCY GENERATOR SIGNAL 246 256 0min? 5 INVENTOR 5 THEODORE A. HANSEN K WM TTORNEY Sept. 2, 1952 'r. A; HANSEN 2,609,452

MULTIPLEX TELEGRAPH SYSTEM EMPLOYING ELECTRONIC DISTRIBUTOR Filed May 28, 1945 s Sheets-Sheet 4 HQ 5 INVENTOR THEODORE A. HANSEN AT TORNFY Sept. 2, 1952 T, HANSEN 2,609,452

MULTIPLEX TELEGRAPH SYSTEM EMPLOYING ELECTRONIC DISTRIBUTOR Filed May 28, 1945 8 Sheets-Sheet 5 STANDARD FREQUENCY FIG. FIG. FIG. GENERATOR CORREOTOR n 5 SlGNALlNG CHANNEL 303 NETWORK f5 SE IF n n II n 3l6 an ale A \A A I 'vw- -vvwv .wv- -MAM ww- I I :p i F 4.4T T T -T-- 1 T m I mvamqn raccoons A. HANSEN TTORNEY Sept. 2, 1952 v T. A. HANSEN 2,609,452

MULTIPLEX- TELEGRAPH SYSTEM EMPLOYING ELECTRONIC DISTRIBUTOR Filed May 28, 1945 I 8 Sheets-Sheet 6 INVENTOR THEODORE A. HANSEN By Wz VTTW Sept. 2, 1952 T. A. HANSEN 2,609,452

MULTIPLEX TELEGRAPH SYSTEM EMPLOYING ELECTRONIC DISTRIBUTOR Filed May 28, 1945 8 Sheets-Sheet '7 INVENTOR T H EOD ORE A. HANSEN Z2 WM I ATTORNEY Sgpt. 2, 1952 'r. A. HANSEN 2,609,452

MULTIPLEX TELEGRAPH SYSTEM EMPLOYING ELECTRONIC DISTRIBUTOR Filed May 28, 1945 8 Sheets-Sheet 8 INVENTOR THEODORE A. HANSEN ATTORNEY 'paratus.

Patented Sept. 2, 1952 UNITED STATES PATENT OFFlCE MULTIPLEX TELEGRAPH SYSTEM EMPLOY- ING ELECTRONIC DISTRIBUTOR Theodore A. Hansen, Park Ridge, 111., assignor to Teletype Corporation, Chicago, 111., a corporation of Delaware Application May 28,1945, SerialN0. 596,295 1 The present invention pertains to telegraph apparatus and'systems, and more particularly to multiplex telegraph apparatus and systems.

' In present multiplex telegraph systems, and apparatus utilized therein, mechanical means are utilized for the transmission and reception of the intelligence signals. While these systems operate satisfactorily there is a maximum speed at which they will operate which is relatively low. At the present time, with the'tren'd towardhigher speed operation; it becomes necessary to provide apbers' of the tube variety.

A still further object of 'the invention is to Claims. (Cl. 178-50) provide an'electronic distributor at both transmitting and receivin stations.

"Another object of the invention is to provide an electronic distributor which may be added as unitsto an electronicsystem wherebythe entire system may be operated at any desired speed.

' A still further object of the invention is to provide an electronic multiplex system which is easily oriented and phased. 1

Y In general, the system contemplatesapparatus at both the transmitting and receiving stations comprising, as fully'as possible, electronic ap- The transmitting station utilizes a a standard frequency generator to initiate voltage impulses which are presented to the tubes of a pulse generator which amplify and rectify the voltage and impress it on the control grid of the tubes of an electronic distributor. The electronic distributor is so constructed that its tubes operate or fire successively, only one tube being operative at one time. The output of the distributor controls a series of secondary tubes which'are'conjointly under the control of a tape transmitter. The secondary tubes, each under the joint controlof a distributor tube and the tape transmitter, cause impulses to be presented to a transmitting relay tube from whence they are transmitted over asignaling channel. A tube is provided to cause the tape transmitter to step the tape after the code signal is transmitted.

. The receiving station comprises a standard frequency generating apparatus and a pulse generator controlling a distributor in a manner similar to that mentioned above, A series of selector tubes are provided which are under the joint control of' the distributor and the incoming code signals. The selector tubes control the code magnets of a multiplex printer or the magnets of an extension arm system for converting multiplex "to start stop code' signals. Sixth pulse control tubesare provided which. are under the control of the distributor and which control theprinting "operation'of the printer and are utilized to extinguish any of the selector tubes which may have been operated. The receiving station is also provided with a corrector network and a phase shift network in order to synchronize and phase the receiving apparatus with respect to the transmitting apparatus.

The general description immediately above has referred. to a single tape transmitter, printer,

.etc. However, such description is for the sake of clarity, and as the present system is for multiplex operation it contemplates the use of a plurality of tape transmitters at the transmitting station, two of which are shown, with the necessary number of tubes in the distributor and in the secondary series of tubes. Likewise, the receiving station must also be provided with the necessary number. of tubes, (both distributor and selector, to accommodate a plurality of channels of operation. For illustration purposes the receiving station has been shown as having a multiplex printer and an extension arm apparatus connected to a start-stop printer with one channel of intelligence goingto each of these printers.

. Overlap is provided for in the present invention as the tubes for controlling the tape feed and printing operations operate only when the apparatus istransmitting or receiving signals over the other multiplex channel.

It might be well to note at this time that the 'tubes utilized in the distributors at both stations are of the 2050 type, better known as thyr'atron tubes.

A more detailed understanding of the invention may be had from the following description with :reference to the accompanying drawings, in .which:

Fig. 1 shows'in block form a diagrammatic view of. the various constituent'parts of the proposed multiplex system;

Fig. 2 shows a relative arrangement of the views disclosing the transmitting station;- j

. Figs. 3, 4, and 5 show in detail the apparatus ;type.

and circuits comprising the transmitting station; Fig. 6 shows a relative arrangement of the views disclosing the receiving station;

Figs. 7, 8, and 9 show in detail the apparatus and circuits comprising the receiving station;

Fig. 10 shows the voltage wave characteristics, in successive stages, as generated by the pulse generator, and j Fig. 11 shows the voltage wave characteristics and relative timing of certain operational sequences of the receiving apparatus.

By referring to Fig. 1 it is possible to obtain a plurality of relay tubes, operating in conjunction'with the tape transmitters and the electronic distributor. The general" description of the receiving station, as shown in Fig. '1, will be postponed until a full description ha's been made with respect to the transmitter station andl'just prior tothe description of the receiving station,

In describing the system and apparatus hereinafter, the various units will be described separately and then in operational combination.

Such description appears to make the apparatus and system more comprehen'dable and understanda'ble.

Standard frequency generator By referring to Fig. 4 it'may be seen that a standard frequency generator has been provided,

which is indicated generally'by the numeral 2!.

This generator "may be anyof those well known in the art and obtainable commercially, but

preferably is of the crystal controlled type in order that theirequency-of the voltage-generated maybe kept within very close limits ofdeviation. The generated standardirequency has the customary A. C. voltage characteristic of'a sine wave.

Pulse generator The voltage generated by the standard frequency generator is passed to a pulse-generator which, in general, co'mprises an amplifier indicated generally by the numeral -'22, a rectifier indicated generally by the numeral 23, and an amplifier indicated "generally by the numeral 24.

With'respect to Figs-3,4, and'5 it may be'seen thata grounded batteryffi supplies D. C. potential over a common "conductor 27 to junction point 28 and thence over a conductor 29 and through load resistors 3| to the plates or-anodes 32 of theamplifier'tube 22. The cathodes'33 of the tube 22 are connected to a commonconductor 34 which is grounded at 35.

The standard frequency which is generated by the unit 2! and which is in the form of a sine wave is fed over conductor 31 to the control grid 38 of the left-hand section of the vacuumia'mplifiertriode tube 22 which may be of the 6SN7 The resulting amplification process, through the operation of this tube','results in an amplified voltagesuch as disclosed as the "curve 39 in Fig. 10. V

The amplified output of; the left-hand section of tube 22 is fed by means of a conductor 4! to the left-hand section of the twin diode rectifier tube 23 which may be of the 6H6 type. A coupling condenser s2 is provided between the output circuit of the left-hand section of the amplifier tube 22 and the cathode 43 of the lefthand section of the twin diode tube -23, to which the above-mentioned output is directed, in order to prevent direct current being fed to the cathode 23 from the D. C'. source over conductor 29,

through resistance elements 3! and over conduc- The'voltage impressed on the cathode 43 of the tube 23 is rectified by the left-hand section in order to remove the positive half of the wave, as shown as voltage curve 44 of Fig. 10.

The negativehalf of the wave output of the left-hand section of rectifier tube 23, as shown as M in Fig; 10, is impressed on a conductor 46 and passes to the control grid 4'! of the righthand section of vacuum triode tube 22. Direct current is applied to the plate 32 of this section of the tube as 'itwas to the left-hand section; namely,fover conductor 29, through resistance element 31, and'through a conductor'efl. The grid ll is normally at zero bias and since only a comparatively small part of the applied negative grid voltage (output of left-hand section of rectifier tube 23) is required to bias the grid 41 to the plate current cut-off valve, there results an output which is in the form of a square wave, as shown by voltage curve 49 in Fig. 10.

The square wave output of the right-hand section of the vacuum amplifier tube 22, as shown as 49 in Fig. 10, is not impressed as such on the input of the right-hand section of the rectifier tube 23 because of a differentiating network. This network, which is comprised of the condenser 52 and the resistance element between the common conductor 34 and the cathode 43, will not pass any direct current. Thus, instead of square wave voltage having the fiat horizontal sections, as shown as '45 in Fig. 10, which has the attributes of direct current at the constant points, a wave having pulse characteristics as shown as 50 in Fig. 10, will be impressed on the cathode 43 of the right-hand section of the tube 23. Likewise, the condenser '52 precludes potential from the D. C. source from reaching the cathode, 33. The tube "23' rectifies the input voltage-removing the positivehalf of the wave and passing the negative half 'onlyQas shown as 53 in Fig. 10, over a conductor 54 to a potentio rneter indicated generally by the numeral 55.

The negative half of the wave thenpasses over a. conductorfi'l to thecontrol grid 58 of a triode tube 24 which-may be of the 6J5 type. The plate ofthe tub-e 24. is supplied with direct current from the battery source 26 over the common conductor 21 to: the junction point28, over a common conductor 59 to a junction point GI, and through a resistance element e2 to theplate. The cathode of the triode, tube 24 is supplied with ground from 35.. Uponthe operation of the tube 24, due to the negative input voltage, --'an .output voltage is-generated which, insteadrof beingnegative, is the positive half of "a voltage .wave, as shown .as 163 in Fig. 10.. .The positive output voltage passes from the plate over a conductor 64, through a The coupling condenser :66 isJprovided so thattthe direct current supplied to the plate'of the tube 24,through the resistance elementfizjmay :not pass over the common con- Electronic distributor The electronic distributor at the'transmitting station is disclosed in Figs. 3, 4, and 5, arranged inthe order shown in Fig. 2. In general, it is comprised of ten gas filled tubes 15 to 84, inclusive, which as previously mentioned, may be of the 2050 thyratron type tubes. It is to be noted that ten tubes are provided in the instant. ar-

rangement because of the fact that the present system disclosed is a two channel multiplex system. However, in theevent that a four channel system were to be used, the number of distributor tubes would be increased accordingly to twenty. In the instant application there is one tube provided for each character impulse for the two channels, making ten in number. Each of the tubes, 15 to 84, inclusive, is provided with a plate or anode 86, a cathode 81, a control grid 88 and a screen grid 89, In describing these tube elements hereinafter, the numbers indicated immediately above will be given followed by the number designating the particular tube to which reference is made.

The plate or anode 86 of each of the tubes 15 to 84, inclusive, is connected over a conductor 9I and through a load resistor 92 to the common conductors 21 and 59, previously referred to as leading from the D. C. source 26. By reason of the anode connection with the positive battery 26 over conductors 21 and 59, the anodes 86 of the tubes will normally have ahigh positive potential impressed thereon. The cathode 81 of each of the tubes is connected by means of a conductor 93 and through an individual resistor 94 to a common conductor 96 which is grounded at 91. The control grid 88 of each of the tubes is connected by means of a short conductor 98'to a conductor 99, connected through a condenser I'I to the common conductor 61, previously re-- ferred to. The conductor 99has a resistance I02 therein which is on the opposite Side of a junctionpoint I03 from the anode lead 98. The end "of the conductor 99 closest to the resistor I02 is connected to a common conductor I04, which is similarly connected with respect to all of the tubes. The screen grid '89 of each of the tubes is connected by means of conductor I06 directly to ciated conductor 93 over a conductor I08 having a resistor' I09 therein and through a second resistor III to a common conductor II2 extending to all of the tubes and similarly connected. A short conductor II3 extends from the conductor I08 and leads to the control grid of a twin triode relay tube I53, for a reason which will be described hereinafter.

Bias voltage from the battery I2I is fed over a conductor II9 to the voltage divider comprised of resistors I I6 and I I8 connected by a conductor II1 and thence from junction point I23 and over I mentioned.

through 91.

a conductor I22 to the conductor I04, previously Thus, it may be seen that the control grids 88 of the individual tubes are normally biased with a negative voltage which is the difierence between the IR drop in the resistor I02 and the negative voltage of the conductor I04. The biasing circuit may be traced from the negative grounded battery I2I, over the conductor II9, through the resistor I I8 to the junction point I23, over the conductor I22, over the conductor I04, over the conductor 99 and through the resistor I02 to the junction point I03, over a conductor I49, through the resistors I28 and I26 associated with the tenth tube 84, over'the conductor 93 and through the cathode load resistor 94 (tube 84), and the common conductor 96 to ground at The screen grids 89 and their conductors I06 are connected to the cathode 81 by means of a conductor I24 extending therebetween. The conductor I24 and the cathode 81 are connected through a resistor I26 to junction point I21 and through a, secondresistor I28 to the conductor 99 associatedwith the succeeding tube 16. The

junction point I21 is connected by means of a conductor I29 and through a condenser I3I to the common grounded conductor .96, previously mentioned.

The anodes 86 of successive tubes'suchas 15 and 16 are interconnected by means of a conductor I32 having a condenser I33 therein. i

All of the distributor tubes 15 to 84, inclusive, are connected similarly as has just been described with respect to tube 15 itself or tubes 15 and 16.

A conductor I34 is provided which connects the conductor SI of the plate 86 of tube 15 through a condenser I35, similar to condensers I33, to the conductor 9I of the plate 86 associated with the tenth tube 84, for a purpose to be later described.

The conductor 9I associated with the anode 86 of the tube 15 is connected by means of a resistor I31 to a conductor I38 which extends to the con- 'to be utilized in a manner and for a purpose as will be described hereinafter. The resistor MI and conductor I42 are connected through'a resistor I43 to the conductor 9I associated with the plate 86 of the sixth tube 80.

A condenser I 44 is provided which is connected between the common grounded conductor-'96 and the common conductor I04.

A start key I46 is connected'to the conductor 99 associated with the control grid 88 of the tenth tube 84 and serves, when the key is depressed, to connect the conductor 99 to ground at I41.

It is to be noted that the conductor I42 is connected by means of a conductor I48 to the common conductor II2, previously described.

Hereinafter in the description of the operation of the electronic distributor, just described as to parts and connections, such description will be made with respect to two associated tubes with no further explanation being given unless there are other elements which act difierently or independently of the tubes described. The descrip- 7 tion-will be made in-th-is manner inasmuch-asthe various distributor tubes 15 to 84, inclusive; oper- -ate-similarly with respect to themselves and to each ether except-as will be'no-ted.

Operation of electronic distributor Dunn-mire time that theei'ectroni'c distributor, asexexnpiifiedby the tubes '15 toM, inclusive; is hotbperatin'g the .plates 86 thereof have impressed thereon'a'p'os'itive voltage and thecon- "trol grids 88 thereof are "biased negatively, as previousl described.

In'the 'event'thatthepulse generator, hr'eviu ry described,' is operatingduring the nonopertime period of "the "electronic distributor, the I positivepulses which aretransinitted to the control'g'rids of the'tub'esfO'verthe common conductor 6 1, will not result in any operation or firing of these tubes inasmuch as "such "positivei'pulse is; notsufiicie'nt to raise the-grid "potential a sum "cientamount to the firing'value of the'tube. Assuining now thatit'is desired tofstart'th'e felectronic'disti'ibutor into operation andthatthe standard frequency generator and the fpu'lsefgen- "erator are operating to transmit positive pulses, 'asindicated at SS'inF'ig. 10, to the commoncon- "duotortl', .previouslydes'cribed, the start button I48 is depressed causing it to "come'into'en'gagement with ground at Ml. As a result'of the "closureof the start button or key E45, an electrical circuit will be established which may be traced'from ground M7 through the start key M6, over "the conductor '99 and through the resistor i'fl2associated with the tenth tube 84, through the "common conductor I04, through the conductor I22 to junction point I23 with the conductor 111, through the resistor H8, and over the "conductor ils'to grounded negative battery l2l. 'It'is'to be remembered that in the previous description the grid 88 of the tube 84 was described as being biased negatively overa circuit which in:luded the membersjust described. As a result of the closure of the above-described cir- "cuit,'the biasingnegative voltage will'no longer b'e prese'nt on the control grid 88 but instead will go to'ground l4? and the biasing potential of the control grid 83 willbe'reduced'to zero. Inasmuch as the 'thyr'atron tubes disclosed in the present 'einbo'diinenthave a firing characteristic which usually isaj'slight negative value,the refdutionofthe Tgrid'voltage to 'zero will result inthe gas in the tube ionizing 'and'in theoperation or firing o'fthe tube 8%.

The operation o'r'firin'g of the tube'84 may be 'traced' in an electrical circuit from positive bat- "tery 25, over the common conductor 2'l,'over' the common conductor 59,'through"the load resistor 92 and "the" conduct'orei associated with the "anode -86 of the tube 8 3, 'to'the cathodes! of this tube (which is nowcon'ducting), over-the conductor '93 through the cathode load resistor :4, and over the cornmon'c'onductorfifi to ground fat 91. Such' a circuit will be establishe'dand the "tube'will continue to fireuntil'such time as external means are utilized to cause the tube to'be extinguished. I

As previously described, a condenser I35 is connected to a conductor LISQ'WhlChj'QihS'the anode conductors Q1 ortubes i5 and 84. During a nonoperating condition of bothofthese'tubes'the mon'denser E35 will 'be in an uncharged condition due to the fact that the conductors 9! of bo'th tubes i5 and 3% will be impressed with a pos'itivecharge from-the positive battery 26, aspreviouslydescribed. "However at such timeas 8 the tube 's-4 operate or fires, as just described, there will I be -a drop in the potential across the anode lead resistor 52 associatedwith thetube 84 hich will=result in thecondenser i35becoi'ning 5 charged. j

As was previously described, the controlgrids '88 ofthe various tubes are biasednegatively'by means of -a *circuit *which includes the cathode and cathode load resistor of the preceding tube. The firing of the'tubelld andthe resuitantelectrical circuit, which was described'as passing through the tube, will have the effect of adding positive voltage to the negative battery circuit, which may-be'traced through the cathode '81 of the tube 84, over thecondxictor-Bt,throughthe i'cathode load resistor 384; over the common conductorf'fifi to "groundat "9T. -As a resultrof 'the addingof positive voltage to the negative battery I21, thebOntr'Ol-grid tie-of tube "1'5 Willbe less negatively biased. The reason for the -decrease inthe biasing voltage of the grid SB isdue tothe increase of current-inth bridge circuit 'whichcauses an increase in the IR drop across the resistor Hi2 associated with the 'tube "15. However, the tube 75 will not operate or'fire at this time inasmuchas wasprevio'usly described, =th -firing value of the thyi'atron tubes-lea slight negative value, which has 'not been 'reached. Thus, at this time tube'l'fiwill be conditioned for operation but will not operate. j

After the-controlgrid 83 ofthe tube -has been conditioned less negatively, the next incoming positive pulsesuch as shown "at 63 i'n'FignlO, of the pulse generator, previously described, passes over the common conductor '6'. and over the conductors 9B and "98'to allof the' igrids 83 of the various tubes. As a result of'such positive pulse'being impressedon the control grids tis ofall the tubes, the biasing voltage of the-grid which has been conditionedwill be reduced from the conditioning Value to a suificiently lo'w v oltage'to fire that particular tube. "As a result of --such reduction in bias potential to the control 3 grid 880i 'the tube 'ISt-his tube vi i-l1 operateor fire.

Itis to'be 'noted'that'only atube Whose grid has been conditionedfias previously described, will 'be'caused tofir'e by the-positive p'uls'eirom the :pul'se generator which, in the instant'description, *is tube'lfi. Inashi-uch asthe positive pulseioriginatihg from the pulse g eiier'ator and the standare rrequeneyeener-ater is -almost instantaneous, -the'control gi'id' will lie-reduced sufficiently in voltage ror'an il scant only and thereafter w ill resume its p'rior unconditioned biasing voltage.

As-was-previously irientioned; each of'theconductors9*3 lea'din 'f-ro'mthe common conductor 61 to'the gr-id -88-is provided With'a blocking'cohreenter I i 81 This} condenser "allows the 'positive eulse from the {pulse generator to pass over the conductor 99 totheig'rfd fiB 'butpreventstheD; C. hiasing voltage from being fed back" to the chili- --nien conductortl.

-Upontheffiringof the tube 75, the iiotri-tial'on the anode 8'5"of-thistubetvhichhas been-reduced due to the lR dr'op across the'lda'd-resistor fl resultsin "a discharge of the condenser l35which i -as" previously" been described as" being charged. Thepath 0f ,disch'argeof the"cohden'ser ['35 may be traced from the condenser, overtheconductor 9|, plate 86, and cathode 81 associated with: tube i5, 'over "the conductor 24, over "the conductor --re and through thecondenser '10! to' the commpn;conductcrrsa ver the common conductor '1 to the'c'ondenser' HlTassociatedwith the tube 84,

ceeding tube for firing and which when such firing occurs results in the extinguishing of the preceding tube through the anode circuit of thefiring tube.

A delay integrating network comprisin the resistors I26 and I28 and the associated condenser I3I associated with each of the tubes has been provided between the cathode 81 and the control grid 88 of the succeeding tube so that the front edge of the conditioning wave (reducing control grid bias from a large'negative value to a less negative value) will not coincide with the firing pulse received on that grid from the pulse gen erator. Such a delay network is'utilized in order to preclude a tube from firing at a time when it is bein conditioned.

The filter condenser I44, previously described as being connected between the common conductors 96 and I04, has been included in the circuit in order to have a stabilizing effect thereon.

It might be noted that each pair of associated tubes 15 to 84, inclusive, are provided with a condenser I33 between the plates 86 thereof. These condensers are similar to and operate in a similar manner to the condenser I35 which was described asbeing between the anode circuits of the tubes 84 and 15. Thus, it may be seen that the electronic distributor willoperate through the continuous successive firing of one tube after the other and the successive extinguishment of the preceding tube upon the firing of asuccessive tube in a manner as was just described. Once the electronic distributor has been started into:

operation by means of the closure of the start key I 46 andas long as the positive pulses are incoming from the standard frequency generator and the pulse generator, the electronic distributor will continue to operate with the tubes 15 to 84, inclusive, firing successively one after'jthe other. It is to be noted that the start switch I46 will be provided with means so that after the depression thereof and the firing of the tube 84, it will automatically open and no longer be in connection with ground at I41 Transmitting ammmtus as is a transmitting relay tube I59. ,-A pair of control tubes I6I and I62 are associated with the A tapetransmitter, I5I and a .pair of similar c ntrol tubes I63 and I64 are associated with the B tape transmitter I52.

Each of the twin triode tubes I53 to I51, in

elusive, isv provided with a cathode I66, a control grid I61, and an anode or plate I68 forming one element ofthe twin tube; the other element is formed of a cathode I10, acontrol grid HI and- As has been, previously a plate or anode I12. I mentioned, the control grids I61 and'I1I' are con-- nected by means of conductors II3 to the output circuit of the distributor tubes 15 to 84, inclusive, through the resistors I09 and over the conductors I08. The cathodes I66 and I10 of the triode tubes are connected by means of a conductor I13 to the common conductor 96 which is grounded at 91. The anodes I68 and I12 of tubes I53 and I54 and the anode I68 of the tube I55 are connected by means of conductors I15 to I19, inclusive, to five contact points indicated by the numerals I to 5, inclusive respectively, of a socket I8I which is associated with the A tape transmitter I5I in a manner which will be described hereinafter. Likewise, the anode I12 of the tube I55 and the anodes I68 and I12 of the tubes I56 and I51 are connected by means'of conductors I82 to I86, inclusive, to five contact points of a socket I 88 associated with the flB tape transmitter I52 in a manner and for a purpose to be later described.

vReferring now to the socket I8I, it is to be noted that a sixth contact point is connected by means of a conductor I89 to the anode I90 of the control tube I62, previously mentioned.

A seventh contact point of the socket I8I is con-' nected by means of a conductor I 9| to a positive grounded battery I92. An eighth contact point is connected over a conductor I93 to junction point I94 of a conductor I96 which is connected to the positive grounded battery 26 but separated from" the junction point I94 by a resistor l91. Inasmuch as the socket I88 is connected simi larly as that described for socket I8I, it does not appear necessary to indicate specifically such connections. It might be noted, however, that the conductor. I96 leading from the battery .26 but separated therefrom by a resistor I91 is con-1 nected to the eighth contact point associated with the socket I88.

Referring now to the control tubes I6I and I62 associated with the A tape transmitter I5I and the similar. control tubes I63 and I64 associated with the B tape transmitter I52, it is to be seenthat the tubes I6I and I63 are each provided with an anode 20.I' which is connected through a resistor 202 and over a 'conductor, 283 to the common conductors 21 and 59,

previously described. The tube, I6I is furtherv provided with a control grid 204 whichis con-. nected by means of a conductor 286 to the conductor I42, previously described, and which has a resistor 201 placed therein; the tube I63 has a control grid 208 which is connected over conductor 209 to the conductor I38, previously described. The tube I6I is also provided with a cathode 2| I which is grounded at 2I2. A conductor 2 I3 is inserted connecting the cathode 2I I to the grid conductor 206 and is provided with a condenser 2I4 therein. The tube I63 is similarly provided with a cathode 2I6 which is coning a resistor 22I therein is connected to the,

anode lead and extends to junction point 222 from whence it branches off into aconductor 223 havin a resistor 224 therein which is connected to the conductor I42, previously mentioned, and aconductor 226 which is connected to a grid 221 of the control tube. I62. The control tube I62 also hasa cathode 228 which is grounded at 229. Inasmuch as the connections .of the control tube I64 associated with the B tape trans- Refer-' mitter |52-are similar tothoseas describedriori thecontrol tube I62; iurtherdescription of them 7 is not deemed necessary.

The. triode transmitter tubec l59.previously: mentioned, has a-control Igride23l which is connected by means of a conductor. 232 to junction point 233 which has branchingtherefrom a con:

ductor 234-having a resistor ZSB'therein-which is-connectedto. the conductor. lflfiat junction point 231 and a .conductor238 having a resistor 239'thereinwhich is connected to thevconductor H9 immediately adjacent the negative grounded battery. I21. The anode 24! of V the tubeaii isconnected over a conductor .2 i2ito .a positive 'battery 243Fandthence overt conductor ZMZto-the resistor 245 .forming partoia potentiometer, inw dicated'generally by thenumeral 241.". There-.-

sistor 24-5 is connected'through. afresistori .2481, over a conductor 249, and through a switch 250'- to a'conductor 251 leading from the cathode 252" The conductors 249'i'and? 251 A negative battery' '255 of the tube I59. are grounded at 253;

is" also provided for: polar operation which. is placed-in the circuit in the event that the switch 250' is moved to its upward position (Fig; 4)

ratherthan itslower'position', as shown fo-r neutral operation.

The movable member of the potentiometer 241 is connected by means of conductor 254to one. contact member 256 offa signal output jack, 7

the opposite contact member 251' oi which is grounded at 258.

Inasmuch astheA and'iB tape transmit ters' lfillandl52'are'siinilar, similar identifyinglnumeralswil-l be'used-for both tape transmitters; and'in the event thatin a description of the operation of'th'et'ransmitting apparatusit becomes necessary to refer to-element's ofthe two tape transmitters, the elements will be described by their common numerals and referencelwill be made to the specific transmitterreferred to.

The tape transmitters. 151 and; I52 are each provided with a r plug; 26! having c eight contact points theeron which is adapted to cooperate with the socket I81.oftheA'tapetransmitter' and the socket I88 oft-he B tape-transmitter. Thesensing controlled contacts of theitapetrans= mitters have beenshov'vn' schematically butcon- 51st of five m'ovablecontacts 253'to25'lginclusive',

which are connecte'ciiover conductors'bearingthe same identifying inumerals to the contact points i" to' 5, inclusive, respectively of the plug26'l.

A bus bar 259*is provided which cooperateswithl all ofithe' inovable contacts? and which is. con nected over conductor 2'; to the No. 8lcont'a'ct' point of theplug 26l;

connectediover conductor 27310 the No; 7 'con tact point of. the plug 251 and the opposite side of whose winding is connected over conductor 214 to the stationary contactmemberwofajswitch indicated. generally by the numeral 216-; The movable contact member of the switch 2T6;is con nected'over conductorii'i'to the'No. 6' contact point of the'plug 26L While: the tape transmitters l5land l52m'ay be of any commercial type, many of which are known in the art, theinstant embodiment contemplates the use of'a tapesensing' mechanism" such as that disclosed in copending' patent application. Serial No.

5613M, filed Novemberi i', 1944', by W. R; Gemmel (exceptingmechanical distributorand dual sens ing devioe'control), oriri Bulletin No. l4l',,Issue. 3, issuedby the. Teletype Corporation; Chicago;

' A tape steppinggsolenoid'i 212: is provided, one'sideoi whose winding is Illinois, initial-ch,1942..v The switch 216 hasbeen provided in:orderto==be able-tocontrol manually .the operation of the tape transmitter 15! Operation of transmitting apparatus In the.followinggdescription of the transmit-- ting apparatus, itwill be assumed that-the con tact point 283 is in a spacing position whereas the contact point 264-is in amarking. position, i as is well known in the art with respect. to such:- ter-minology. The spacing condition indicates be in engagementwiththe busbar 269: It is-to be understood, however, that theremaining contact points 265 to 261, inclusive, will'be ineithera marking or spacing condition, depending on thesignal perforated inthe tape; in accordance with the Well-known five unit Baudot' telegraph code.-

Aspreviously:described, the output circuitof thedistributor tubes 15-to fi iyinclusive; are'each connectedby means ofthe-conduetor 93, the conductor I08 having the resistor Hi9 therein, and the conductor H 32- to the control grids I6? or l'H'of the twin triodei tubes I53 tov I5 1; in

clusive Assuming in'the-instant examplathat.

thetubeJE-is in its. unoperated or; nonconducting; condition, the grid 1 51" of theleit-hand :section ofIthe tube l 53=will bei.biased to a negative value IR drop acrossthe resistor Ill and the negative" battery I21: ofa-. circuit which; may, be traced fromg-round at 91, overthe conductor 96throughlthe resistor 96,- overtheoonductor- 08, througlrthe resistor 139,- through there sistor HI, over-the conductor H2, and over :-the

conductor l l9 to groundednegative battery I21.

Under this condition withlgrid; iii? of the tube:

153'" being: biased negatively beyondv its cutoff value th-e tube i53 will be-non-conducting:

Assuming, however, that the tube 15-) is. now

'operatingas has been described with respect to the operation of the'electronic distributor, the

output voltage of the tube 15 may be traced, as previously described; from the cathode 81, through the conductor 93 and the resistor 94. Due to-theaddition of" such voltage there will result a: further potential drop across the. resistor'ilk which will cause an increased IR drop, across theresistor HI and the negative battery i2! whichcauses'the grid 16'! of the tube I53 -no longerto be biased'negatively but instead to be increased to zero voltage. As airesult of: such change-to the grid It], the tube 153, or at least.

the left-hand section thereof comprising, the

anode" I68 'an'd'the cathode 166; willbecome con-- ditioned for conducting depending on a conditionnow t'oibe described.

As previously mentioned; in the instant" ex? ample; the contactpoint 253 is in itsspacingposi tion' but otengagement withfthe bus bar. 2I69l As: may be" seen byjreierringtothe drawings. under such ccndition'th'e positive groundedbat- Such negative bias occurs due to the tery 26, which is connected through resistor I91 to junction point I94 and over conductor I93 to the eighth contact point of the socket I8I, and which in turn is connected through the eighth contact point of the plug 26I and over the conductor 210 to the bus bar 269, will not be impressed through the contact point 263 on the conductor associated therewith bearing the same number becausesaid contact point is open. As a result of such condition no electrical circuit may be traced through the conductor 263 to the No. I contact point of the plug 26I, through the No. I contact point of the socket IBI, and over the conductor I15 to the anode I68 of the lefthand section of the tube I53. Thus, while the tube I53 has been conditioned for conduction because the grid I61 has a zero potential applied thereto, the tube will not conduct.

Under the above described condition with the left-hand section of the twin triode tube I53 not conducting, which occurs when the tape sensing mechanism associated with that particular tube element is in spacing position, a condition exists whereby the voltage of the grid 23I of the transmitting tube I59 is zero. Such condition may be seen by reference to the bridge circuit associated therewith which may be traced from grounded positive battery 26, through the resistor I91, over the conductor I196 to junction point 231, over the conductor 234, through the resistors 236 and 239, over the conductor 238 to grounded negative battery I2I. Because of the values of the negative battery I2I, the positive battery 26 and the constants of the resistors I91, 236 and 239 under the above-mentioned condition, the control grid 23I of the transmitter tube I59.will have a zero grid voltage. Inasmuch as the transmitting tube I59 controls the transmission of outgoing signals to the signaling channel, not shown except schematically in Fig. 1, the following condition will exist as a result of the zero condition of the grid 23I. Because of this zero condition of the grid, the tube I59 will be conducting and a circuit may be traced from ground 253 through the switch 250 which is in its lower position for neutral operation, over the conductor 249, through the resistor 248, through the resistor 246 forming part of the potentiometer 241, over the conductor 244, through the positive battery 243, over the conductor 242 to the anode 24I, through the tube I59 which now conducting, to the cathode 252 and over the conductor 25I to ground at 253. Likewise, because of the potentiometer 241, a circuit may also be traced from ground 258, through the one contact element 251 of the signal output jack, through the second contact element 256 thereof, over' the conductor 254 to the variable member of the potentiometer 241, through the resistor 246 with which it is in engagement, over the conductor 244, through the positive battery 243, over the conductor 242 to the anode 24I of the transmitting tube I59, through the tube- I59- isting.

Following the assumptions previously. made for the instant description,consideration must now 141 be given to the condition whereat the contact point 264 is in engagement/with the bus bar 269 signifying a marking condition. In order to complete the desired description it will be assumed that the distributor tube 16 is firing, thus conditioning the right-hand section of the twin triode tube I53, as exemplified by the anode I12 and the cathode I10, for conduction. Under this condition it is to be remembered the control grid I1I of tube I 53 will have a Zero voltage impressed thereon, as previously described. When such condition occurs, an electrical circuit may be traced from ground at 91, over the common conductor 96, over the conductor I13 to the cathode I10 of the tube I53, through the tube I53 to the anode I12, over the conductor I16 to the No. 2 contact point of the socket I8I, to the No. 2 contact point of the plug 26I which willbe in engagement therewith, over the conductor 264 to the contact point 264 now in engagement with the bus bar 269, throughthe bus bar 269" and over the conductor 210 to the No. 3 contact point of the plug 26I to the No. 8 contact point of the socket I8I, over the conductor I93 to the junction point I94 with the'conductor I96, and

through the resistor I91 to positive grounded As a result of the circuit just dethe voltage drop across the resistor I'91 upon the conduction of the tube I53. At such time as the transmitting tube I59 becomes nonconducting no electrical circuit may be traced from the positive battery 243, through the tube and over the potentiometer 241 to the signal output plug as exemplified by the contact members 256 and 251, and, therefore, a zero line current condition will occur on the signaling channel. Thus, it may be seen that when the tape sensing mechanism is in a marking condition, as just described, a zero condition will occur on the signaling channel. Inasmuch as the operation of the triode tubes are under the direct control of the output of the distributor tubes they will cease to conduct aiter the associated distributor tube is extinguished.

In'the event that polar operation is preferredto the neutral operation just descrilzxed,v the switch 259 should be positioned in engagement with its upper contact point, rather than in engagement with its lower contact point as dis-.-

closed in Fig. 4 of the drawings. Assuming the same conditions that have been described above, a

in the event that a spacing conditionexists, the

tube I59 will be conducting and an electrical circult may be traced similar to that tracedabove with the exception that it must be traced through the negative grounded battery 255. However,

because of the values of the battery 243, the

negative grounded battery 255 and the constants of the resistors 246 and 248 anegative signal will 5 still be transmitted over the; signaling channel through the jack exemplified by the contact, ele- 1 ments 256 and 251. In the event, however, that a marking condition exists; the tube I59 will no longer be conducting, as was described with re-;

spect to the neutraloperationabove. It is to be remembered that under theneutralloperation, with a marking condition that the tube-r159 was;

not. conducting: and a zero condition existed on the: signaling: channel because no circuitcould betracedfrom thebattery 243 through the tube I59; Under the polar operation it is still true that'snoz circuit can be traced through the tube I59;forthebatt'ery 243. but, however, under this condition acircuit may be traced from ground at: 253;v through. the. negative grounded battery 2.55,.through the switch 250. which is now in engagement with its upper contact point, through thezconductor; 249 through the resistors 2st and 246, through the. movable member of the potentiometer 241m engagement with th resistor 246; and overtheconductor 254 to the one contactelement' Biof the output jack, through the second element-25T1'whichis bridged with the element1256-bymeansof a plug for the signaling line to: ground at: 25.8. As the negative battery 255iis grounded'at253' a positive impulse will be transmitted over the signaling channel. Thus, it: may be seenthat under the polar operation when; a spacing condition exists in the tape sensing=device= and thetube I59 is conducting, a negative impulse: will be transmitted over the signaling channel identical as in neutral operation.: Howevenwh'en a marking condition exists a positive impulse will be transmitted over the signaling. channel instead of the zero condition which exists-during neutral operation. It should be=noted; however, thatthe present receiving apparatus" to' be described hereinafter will not operate on polar signals without intermediate means to alter the positive impulses to a zero value prior. to'their conduction to the selector tubes; Such alteration maybe by means of an electronic relay; etc.

Itis to be noted that the abovedescription has referred-mainlyonlyto the A" tape transmitter and the relay tubes associated therewith. How-- ever,- it' is to-be understood that the B tape transmitter l52-"and its associated relay tube and apparatus operates similarly to that described with'respect'to-the-A tape transmitter l5| and fonasirhilar purpose. Inasmuch as the distributor'tubes 15108-4, inclusive, fire successively they therefore condition successively the individual tube elements of the twin triode tubes I53 to I57, inclusive. Therefore,- the first five tube elements cooperatewith the Atape transmitter and the transmitting tube to transmit coded impulses F over-the signaling channel, whereas the second five distributor tubes cooperate with the B tape transmitter I52 and the remaining five tube elements of the relay tubes; to cause signaling impulsesto be transmitted from the transmitter tube I59 over the signaling channel which are representative of the intelligence in the B channel; Thus, in this way two channel multiplex-operation is'provided.

Previous mention was made of the control tubes I61 and H52 associated withthe- A tape transmitterl5l and the control tubesl 83 and I54 associated w-ith the*Btape transmitter [52; These tubes; which operate under thecontrol of distributor-tubes, are utilized to step the tape in the tapatransmitter-in a manner which will nowbe described; Inasmuch as the control tubes NH and H52 operate in conjunction with the A tape transmitterand the control tubes I63 and IE4 operate in-a similar manner withre'spect to the B- tape transmitter,- description will be made of theyoperation of the former tubes only.

Inasmuch as it-"i's not desired to step the tape transmitter until such time as all of its conditiens, assignified by'five marking and/or spacing impulses in any order has been impressed on the associated relay tubes, these control tubes are;-

conditioned by and under the. control of the fifth:

and sixth distributor tubes 1% and 30 for the control tubes I61 and 62, whereas the: control tubes: I63 and i6 1 associated with the B tape transmitter 152 are conditioned byand under the control of the tenth tube 8'4 and the first tube 75.

The fact that the fifth tube 79 partly initiates theacticn of these control tubes will not result in a stepping of the tape prior to the conditioning of the relay'tube associated with the distributor tube 79 and the fifth code impulse, as signified by the contact 261, inasmuch as the operation of the relay tube and distributor tube will be substantially instantaneous, whereas it is necessary for tape stepping that the two tubes cooperate to cause such condition because of the length of time necessary for the actual stepping operation.

Referring now to the drawings and especially Figs. 3' and 4 thereof, and assumin that the dis-- tributor tubes 19 and 80 are not operating or firing, the voltage of grid 204 of the control tube IBI will be zero and this tube will be conducting.

Such zero condition on the control grid 204 may be tracedfrom positive grounded battery 26, over the conductor 21, through the resistor 92 associated with the tube 79, through the resistor I41, and over the conductor I42, through resistor 201, over the conductor I 48, and over the conductor H9 to negative grounded battery iii. A second circuit may also be traced which instead of going through the resistor 92 associated with the tube 19, passes through the-resistor 92 associated with the tube tiland through the resistor M3 to the conductor 142'. As a result of such circuits, as

just-described, the grid voltage'of the tube I6l will be zero and-this'tube will conduct overa circuit which may lee-traced from groimded positive battery 26, over the conductor 27, over the conductor 2il3' and through the resistor 202 to the anode 201, and through the tube lfil to the oathode 2H and to ground at 2 l2.

Under the condition just described with the distributor tube 19' and 86 not firing and with the tube 16] conducting, the control tube Hi2 will not be conducting because the control grid 221 thereof will be biased negatively. The reason for such negative bias at this time is because of the potential drop across the resistor 292 at the time that the tube 16! is conducting. The circuit for'controlling the bias of the grid of the tube 152 may. be traced from negative grounded battery 12!, over'the conductor H9, over the conductor 148, over the conductor 223 and through the resistor 224, through the-resistor 22!, over the conductor. 2 l9, through the resistor 202, over the conductor 203' to thecommon conductor 27, over the common conductor 2'! to positive grounded battery 26.. As just mentioned, because of the potential drop across the resistor 292 while tube IEI is conduct ing, the grid22'l o'f'tube I62 will be biased negatively and this tube will not conduct.

Let us now assume that the distributor tubes 15.

*to T8, inclusive, and their associated relay tubes described and the voltage impressed on the grid. 204 of thecontrol tube It! is at cutofi value orv biased negatively. Under this condition the tube lfi i wili no longer be conducting inasmuch asin such triode tubesthe. conducting. is directly-under.

the control of the grid. Under the condition of '17 the control tube It, not conducting, the potential drop across the resistor 202 will not be as great and the voltage impressed on the control grid 22'! of the tube I82 will be altered to such an extent, over the circuit previously traced for said control grid impressed voltage, that the tube I62 will become conducting. At this time a circuit may be traced from grounded'positive battery I52 associated with'the socket I8l, over. the conductor l9l to the No.7 contact point of the socket to the No. 7 contact point of the plug 26!, over the conductor 213 and throughthe winding of the solenoid 212, over the conductor 2M, through the switch 216 which is now closed, over the conductor 211 to the No. 6 contact point of the plug 26! to the No. 6 contact point of the socket IBI, over the conductor 189 to the anode I90 of the tube I52, through the tube which is now conducting to the cathode 228, and to ground at 229. Thus, under this condition the energized solenoid 212 will cause operation of mechanism to step the tape in order that a new codal combination may be presented to the tape sensing mechanism. It is to be understood, as is well known in the art, that during the tape stepping operation mechanism is provided for withdrawing the tape sensing members from perforations in the tape, previously sensed.

As previously described, the controltubes It! and I62 are under the joint control of the distributor tubes 19 and 80. Likewise, as previously described, after the distributortube 19 has fired it will condition the succeeding tube 80 for firing which, when that occurs, causes the extinguishment of the preceding tube 19. Therefore, assuming now that the tube 19 is no longer firing but instead the tube at is firing, a similar circuit and condition may be traced for causing the tube It! to be nonconducting, the tube I62 to be conducting, and the solenoid 212 to be energized. The joint control of these two tubes for causing the tape stepping operation is necessary because ofthe duration of time consumed in the tape stepping operation;

It is to be remembered that condensers 2M and M8 were described as being between the cathode and grid of the control tubes I61 and 163. Such condensers have been provided because, as previously described, the operation of the distributor tubes is substantially instantaneous and, therefore, by providing these condensers an abrupt application of voltage to the solenoid 212 may be prevented. Thus, the voltage impressed thereto will be somewhat smoothed out in order to achieve more satistfactory operation thereof.

" Transmitting station The operation of the transmitting station, as disclosed in Figs. 3, 4, and of the drawings, has been described in detail with respect to the various operations thereof. Reiterating briefly the various operations and apparatus described above, it has been seen that the standard frequency generator 2| generates a standard frequency controlled within narrow band limits which is in the form of a sine wave. This voltage is; then amplified and rectified by means of the pulse generator exemplified generally by the tubes 22, 23, and 24, to initiate a positive pulse, such as shown at 63 in Fig. 10, which is timed in an invariable succession. The electronic distributor, as exemplified by the thyratron tubes to 84, inclusive, when once started operates in timed succession with the positive pulses generated by the pulse generator. Likewise, it has which it is connected so that, a particular relay tube will conduct or not conductfdependingon the joint operation. of the associateddistributor tube and the tape sensing contact, depending also on whether the contact is in markingor spacing condition. l1

A transmitting tube is provided, as. desc which is under the control of the relaytubes and which through successive operations or nonoperatipns, depending on whether marking or spacing selections are set up in thetape sensing contacts,

causespermutation code signals comprised of .fiv e impulses'each to be transmitted over the signaling channel.

Thus, by a combination of the electronic. ap- I paratus described above, it is possible to transmit code signals over a signaling channel .with no movingmechanical parts, with the exceptionlot the tape transmitters.

Receiving station By referring-to Fig. -1, the various component parts of the receiving station have been shown diagrammatically and comprise, in general, a standard frequency generator, a corrector'network, a phase shift network, an electronic receivingunit, a multiplex printer, and a start-stop printer operating in conjunction with a multiplex to start-stop converter. It is-obvious that two multiplex printers could be utilized instead of a start-stop printer, but for description purposesin order to show how start-stop apparatus could be adapted to such a system, the disclosed apparatus is included. It is to be noted that both'theelectronic receiver and the corrector network are connected to the signaling channel over which permutation code signals, originating from the transmitting station just described, are received.

The actual elements and circuits comprising the receiving station maybe more readily seen by reference to Figs. '7, 8, and 9 arranged in the order shown in Fig. 6.

With respect to the electronic receiver, such apparatus may be broken down into com onent parts which include a pulse generator, an electronic distributor and selector mechanism which will be described hereinafterseparately, as was done with respect to the component parts of the transmitting station.

Hereinafter, apparatus which is similar toand operates in the same manner as that described with respect to the transmitting stationwill' be identified and reference made to such similarity only if a complete operational descriptionis not necessary for an understanding of the present receiving station.

Standard frequency generator 'thereof is necessary other than to'say thatjsueh ously.

"generator is preferablycrystal controlled for a reasonwliichwillbe descnbed hereinafter-w The output of the generator 30 l is; as usualwith such units, of a sine .wave characteristic:

Corrector-network:

'A-corrector network which-has been. indicated generally bythe -n-umer al;3'0 2 ispmvided, which is'vcpnnected. to thesignaling. channel. by means of a conductor.- 311i and vtothe. standard frequency generator 301. by. means? of a. conductor. 30. 4.

Themorrector network. 30.2.is fully described in foo-pending patentjapplication, .Serial .No. 601,818,

filed on June 27, 1945, in the name of; Snhuler, inventor. It..is notdeemednecessary to describe further the. operation of. the, corrector Qnetrvork. inasmuch ,as suchis described,- fully. in .the, alioveeidentii'led copen'ding, application.

HDWeyen. it. is. pertinent to. note. that. the. cor.-

.rectarnetwork. 3.02operates toualterv the standardLi-requency, generatedby thegenerator 3111 .by

altering the impedance in the crystal circuit which. controls .the operation of. such generator.

Such .1 frequency, alterationresults. from a. comnarison of, theincomina sienals,.-over. the con.-

diictor. 30 3. andrstandard, frequency. generated in order that the apparatus at. the. receiving station may operate synchronously with respect to the apparatus at the transmitting station.

Phasashift networkits-transmittal? to the-pulsegenerator tobedescrihedi'hereinafteri Inasmuch as such. a: phase shifttnetworks-is well known: in: the art it isnot deemedznecessary to further-describeits elements orioperation;

Pulse generator fl'hewpulse finerator. utilized. at the receiving station. and which is exemplified by, amplifier tube 30i8,,rectifier. tube 3119 andv triode tube.3l-l

isconnectedto thephase 'shiftpnetwork 3116 by meansxof'. a conductor. 3:10. As was described with respect to the transmitting station, a sine wave isJtransrnittedover the conductor 31! to theleit-handelement of, the amplifier tube 308 from whence, itis rectified and amplified similarly. to. that sh-own.in, progressive steps in Fig. .10; identically, as was. done at.th.e transmittin station. Inasmuchas the, elements and circuits in the present pulse generator are similar to and operate in.the same manner as previously. described}. no further description appears. to be necessary.. It isto be noted however, that a condenser. 312. has been provided'in order .to increase. the'output ofgthe pulse generator. The

.Qutput'oithetriode tube 3| [which has a similar wave characteristic to that shown as B3 in Fig. 10 is impresesd over a conductor 313 to a common conductor- 31k and thence is. impressed on all of the control grids of the tubes of the electronicdistributor.

Electronicdistributor.

Anelectronicdistributor which is; exemplified bysthethyratrontubes SilEto 325, inclusive, has

heen provided which operates similarly-to the electronic distributor described; in detail" previ- As; mentioned-z-i above, the positive impulses oiithe outputacircuit .of the tr'iode tube 3 1 El are transmitted over a. conductor '3l3'; to the common conductor-31. which lead'sto-the; con.- trol grids of all of the thyratron tubes 3'I'G t0 32:5, inclusive. A start key. 32:1:is provided which upon the-operation thereof will cause the tube 325 to fire, and thereafter'resultsin thetubes3l B to- 3 25; inclusive, firing successively. As each tubefires, it causes the extinguishment: of. the prior tube. Inasm-uchas thisoperation hasbeen fully-described her-einbefore, it is not necessary tofurther describe either the elements or the operation of the electronic distributor'other than to saytha-t the output oft-heindividual tubes upon fi'ring is appliedov-er a conductor 32-8 associated-with each of the tubes. Theoutput of the distributor tubes 3%- to 32 5, inclusive,- which isapplied to the-conductors 328-takes the form of -a square--Wave, as shown at 32 9' in Fig. 11.

Selector apparatus The-selector. apparatus; includes; ingeneral; a plurality. of .f gas =.fi1led-. thyratrontubes; 33 I- to; 3*), inclusive, and: two; similar gas filled: sixth: pulse tubes13.42:and1343f; A. pair of. relaysjndicatfid generally; by the numerals; 344. and: 345: are; provided which operate in a manner and for a: D11 pose .which. will .bedescrihed: hereinafter;w

With reference, to .the tubes .3131 .tcniidfl', inclusiv-e, the control: grid? 3417 of: each of. these-tubes is .connectedrover :aaconducton 34 8, and thifouf-jliv a condenser 349; to; junction point 355]! with the conductor 32:8, previously.-- mentioned;. leading from the outputof" the distributor tubes. The cathode.352: of. each of thesetubes isz connected overa common conductor 353..tojunctio-n.p0int 422: and. thence to ground: atyItEA: The screen grid 358 M. each of: theitubesisconnected, to a common: conductor-351? which is connected; by means of a conductor- 35B tothe one contact member 359 Ref a signaling input-j ackhaving the other: contact e1ement 36t| connected over a. con:- ductor 36-2 to junction point..422tand;t hencet0 groundat354: The input .j-ack receives the-signal impulses i'romlthe signalin-gchannel; Aline terminating resistor: 3&3; isaprovided between the conductors 358i-and-j 362 for a. purpose which is well known tothe telegraph art. Theanodes 3'fi 4 of: the various-selector-tubes 3.31 to- 335, inelusive, are connected through the individual load resistors-366* and -over conductorsfidl to. 3'! l. inclusive. respectively, to .five c-ontact-points-Nos. i to 5, inclusive, of a socket: 3-13. A sixth. contact point of the: socket-3132 is connected over-a conductor 374 and through a resistor 315 to an anode 316 of the sixth pulse tube 343', previously mentioned. A seventh contact point of, the socket; 31 3 is-c-onnected.over a conductor 3,'|| and through a, condenser 3,1 8 to junction point 319 andthenee-over conductor. 38] to grounded positive-battery 332. The, condenser. 3.l8.i s provided to preventsparkingofi the-contacts ofthe relays 34.4 arr-6,534.6;

Inasmuch as, the selector tubes.- 336 to, 340, inclusive, are connected similarly, to; that. describedfor. the tubes 33!. tov 335, inclusivewith the exception thattheyterminate in a socket .383

instead. of socket.3l 3, nofurther. descriptionwill be made thereof. It is to be noted, however, that the sixthicontactpoint of the socket 383..is;con-

nected tothe anode of thesixth. pulse tube 342 and. the. seventh contact point is, connected through; the armature of; the. relay. 3.44 to; the positive-battery 38 2...

-The five tubes 331 to 335, inclusive, are responsive to the A channel incoming signals, whereas the tubes 336 to 340, inclusive, are responsive to the 13 channel signals, in a manner to be described hereinafter. The sixth pulse tube 342 operates in conjunction with the first distributor tube 316 whereas the sixth pulse tube 343 operates in conjunction with the sixth distributor-tube 321. V

"In order to trace the connection: between the tube 342 and the distributor tube 316, it is'to be seen that the output circuit of the tube'316-,'Which is impressed on the conductor 328 tojunction point 351, is further impressed over a conductor 386 having'a condenser 381 therein to a junction point 338 which is connected to a conductor 389 leading'to the control grid 391 of the tube 342. The conductor 386 is joined at the junction point 388 through a resistor 392 to a conductor 393 which is connected through a resistor 394 to the control grid 396 of the tube 343, and which extends over conductor 391 and through a condenser 398 therein to the output circuit of the sixth distributor tube 321. The conductor 393 is also connected beyond junction point 480 by a conductor 399, over-conductor 481 to a common conductor 482 which is connected by means of resistors 483 to the conductor 348 associated with the control grid of each of the tubes 331 to 348,

inclusive. The conductor 481 is formed with the movable member484 ofa potentiometer, the resistor 486 of which is connected through resistor 481 to ground at 498. The opposite side of the resistor 486 of the potentiometer is connected through resistor 489 to a commonconductorfl I which is connected over conductor 412 to grounded negative battery 413. The conductor 41 1 is'connected over conductor 414 andthrough condens er416 therein to the junction point 411, intermediate the resistor 481'and ground at 468. The sixthpulse tube 343has a screen grid 418 which is connected by means of conductors 419 and 421 to the conductor 362, thence to its junction point 422 with the conductor 353, and to ground at 354, as is the screen grid of the tube 342. The cathode 423 of the tube 343 is connected over conductor 424 to ground at 354.

The relay indicated generally by the numeral 346 is formed of a winding 426, one end of which is connected through resistor 421 and over conductor 428 to the conductor 314, previously mentioned, and the opposite side of the winding is connected over conductor 429 also to the conductor 314. It is to be noted, however, that the conductors 4 28 and 429 are connected to the conductor 314 on opposite sides of the resistor 315. A condenser 431 is providedbetween the conductors 428 and 429 immediately adjacent the winding 426. An armature 432 is provided for the relay 346 which is connectedover conductor 433 to the conductor 3'11, previously described. When the relay 346 is in its-de-energized condition the armature 432 is in engagement with a contact point 434 which is connected over a conductor 436 to a conductor 431 which is joined tothe conductor 311, previously described, at'junction point 319. v v r "IA plug 441' is provided which cooperates with the socket 313 and which has-the'contact points 1 to 5, inclusive, connected over conductors 442 to 446, inclusive, respectively, to one side of the windings of individual magnets 448 to 452, inclusive, respectively, of a multiplex printer ind1- cated generally by the numeral 453. Such a multiplex printer may be similar to that dis- 22 closed in U. 8. Patent No. 1,665,594, issued to H. L. Krum on April 10, 1928. The opposite side er the windings of the magnets 448 to 452,- inclusive, are connected over a commonc'onductor 454 to the No. 1 contact point of the plug 441. The No. 6 contact point of theplug 441 is connected'over' a conductor 456 to one side of the windingof 'a start-stop side also which impresses the converted signals over a conductor 461 to a single magnet start-stop printer, indicated generally by the numeral 462. With respect to the instant apparatus described, the multiplex to start-stopconverter 459 may be similar to that disclosed in U. S. Patent No. 2,382,596, issued on August 14, 1945, in the name of W. J. Zenner. Likewise, the single magnet start-stop printer 462 may be'of the type disclosed in U. S. Patent No. 1,904,164, issued on April 18,1933, to S. Morton et al."

Operation of selector apparatus- In the following description of the selector apparatus it isto be assumed that the standard frequency generator 381, the corrector network 392, the phase shift network 396, and th'epul'se generator, as exemplified by tubes 388', 389; and 31 1 are functioning properly to present apositive pulse over the output circuit of the tube 311170 the conductor 313 and to the commonconductor 314, similar to the positive pulse disclosed onthe voltage curve 63 of Fig. 10. Likewise, it is to be assumed that this positive pulse, which is presented to the control grids of the electronic distributor tubes 316 to 325, inclusive, causesthe operation of these tubes successively in a man ner which has been described with respect to the electronic distributor at the transmitting station. Likewise, it is to be assumed that the incoming signal from the signaling channel to the signal input jack is composed of a code signal having a spacing and marking characteristic for the first two impulses, as described with respect to the transmitting station. j

Such input wave characteristics may be seen by reference to curve 453 in Fig, 11, wherein alternate spacing and marking impulses are shown. Through the use of the phase shift network 366, the distributor tubes can be caused to fire vari ably out of phase with respect to the incoming signals, as may be seen by comparing curves 329 and4630fFig.11. Assuming that the distributor tube316 is in its nonoperating condition, a circuit may be traced from ground at 488, through the resistor 491, through the resistor 406 of-the potentiometer, through the resistor 409, overt-he conductor 4'11, and over the conductor '4-12 to negative grounded battery 413. This circuit acts to bias the control grid 341 of the selector tube 331 negatively in such a manner that the tube will not fire. Assuming now thatthe distributor tube 316 is firing in synchronism with the incoming spac ing impulse, the control grid 341 will no longer be biased negatively; but because of the output-of The contact points of the plug a he} dis ributor: tube: 15,& ill; be aised; 9: aizere e tese value."

Theou nut f; the; ra iousidis r bu or; tubesi 6; etch, s nrer on yl esc bed s. av ng. a c arac erist snQh'- as-.- ha h n. 32% B .11. Hstwe n due;- to h n e ser 49- being te med ate; hesgr d 3.2" a c lthe ut ut circ itof he; distr h or; be, a. p siti e ulse uch, as that own incurs e4 4; rEie- 1;,1; w llihep esen itm the en ral r d; nste d; f the s ua e,- wav oraise; t a; zero; lue- Atthesame time-asthe co trol grid wi h? selec or ube 1; raised. o ero... oltage.- the ne ati e:- iiacingz pnsliti n whi h. exis s n. he i iia ih z hannelw ll1. e; mp e d-.Qv rhe onact member. 35.94, QYer -the 9n i uctq. 35 v r hez emmonicendu tor 3. 1 to; hescmensfidfififi of;the sclectortubefit Becaus h wever; i.

theine at vepetent alentice-screen rid; ,the nbe 13i wi l no zfire: eve u h hc o rol eridwas etza er ivoltaeel. Thusidur hea spa n ndi: ime; m heas ena ine hannel; the asso atedse: lentortubfi will notrfife; even thou hitre e resa onditinoing pulseifromits associated distributor tuber Inasmuch as the selector-tube '33! does hi -fire, no electrical circuit can be traced over, its; output circuit throu h the resistor .366; over the -conductor=351 to the No. I contact point of; the socket 313 to the No. I contact point of the plug 441, and;th ence to the Winding of the magnet 448 of the multiplex printer 453. Thus, during a spacin condition, at which time the associated selector-tub do snot perate-0r fire, the-a sor Qiated; multiplex printer magnet likewise will not beenergized. It isto be. noted that after the distributor tube 3"; ceases to operate, the control grid- 34'! of the selectortube 33| will no longer be at the zero voltage; but instead will be reduced to a negative; bias, as previously described for the nonoperating condition of the distributor tube 318-.

It; is to be noted, as hesbeeh, described previonsly, that the output of the distributor tubes whichhaye a square wave characteristic as shown as curve 3290f Fig. 11 is altered by means of the condensers 349 so-asto assume a pulse characteristic; asshown by-curve 464 Of-Fig; 11 Such a ond ti n e t enha ces the p rati n. of the apparatus becanseof the point selection which ii-possib e; By his t rm s. meant t e, a t ha the; c ndit onin m lse f om th i uto ubes: salmost irmtantanepusand thusw i. cause the operation of the selected selector tube when DIQQI S HQUIIBBHY. at any P t n th i n impulse. Such operation i extremely desirable because itno longer is necessary to rely on the nal imp lseb ine-pre t r red m ne time, and. Qf'sutficient volume in order for it to be received. This; condition isparticularly valuable when. Signaling conditions are poor and the received signal impulses are mutilatedwith respect to. ideal signals asshown by curve 463- of Fig. 11. Underthese-conditions-it is only necessaryto have the conditioning-- pulse concurrent with v the best portionof the signal impulse to insure proper operation, It; isv also to be noted that the point selection, thatis, the degree of building up of thc pulse and itsduration may be altered by altering: the; constants of; the circuit.

As m; rationed above, it is possible to shift the onditio in pulsefr m the, distributqr' u s so as:v o be: concurrent Wi h. hev best-part of th si nal-impuls uchrshiit y ema e: within the; imits of the, s na impulse interval. as

shown y: curve; 4.63:- Qf. E e"; iLby-g m ans: or: th nheswshiit: netwo k..discl0 d inbiwk diagram Fig l, Itis to be seenby-referenceto Eig ll and-"by a co p riso qfflcurvesi lesi and l t hat he pulse; s -r e t he midno nt; of: the; nal. nte val: the p esent isclosu e2 e ause: u der normal. di io s; h mpuls s maximumpat hi p int- It mi ht e. nt o ed; that ea er:

rector network designated 303 andidisclosed fnllyn he ah vemen onedlR, G. Schiller natentapnlicatio will. tendtoa t0matica 1y set; henu se with respect: tqmheisisnaL mnulsesr Through. heper ionf hese ne w rks e; distribu r and selec r. tuheswiilppe a e. n p m m: Phase with; re pect; to; he; inc ming; ignal mpulses.

A suming; newthatfihe 1 is ributor; tube- 3.111. 15-

firing; in: syn hr nism; w th; he' nc min 1.11MB.-

ihe;iz nulseitromt he ienalin cha nelidescu ibed will hav a zerow ta c a ue: nd-.unden-snch:a-

o d t the se ec ortnbet 3.2; willfir Und r-such: o d t n: an e ricalmir uitzmey be; t aced romer nd-atnfitr over th co ductor 3. 3m the: cathode; o he: selector tube: 331-, hron h- .the tuheswhiehisnowfir ns'-' 0: hc-anode 5 throuehtheresistm andtye 319409. 1? octor 36.8 il he No: 2 co tact: p nt it; h 0cict;3:'l3 o. he No. 2i cntacttnoin r f;thhplue I; over the conductor-V 443, through the-winding of: the-ma net hrouehth o mencemcluctor QBeivt the- 1 Co tact nointifi-theepln 44 1 and to the No; Icon-tact Qfjthe: socl:et;3'13, overthe conductor 31?; over the conductor; 433, h u h he arma u e; 32 ofr he relay- 346i new de-energized);, through the contact 484:;associated wi h-,4 h a mature and e heconductor: 436. over the conductor-- 43 1 to, thegjunction; point 3? 9, and over the-conductor -38j-1togroundedpositiye a tery 82.; t m hte not d'th becausehe, condenser: 3 8 he, ondu or 3 .1, a: ci cui may not: be; tra e d ect over;- th conduc or 3 1 ome-bat ery ut st e t a edthrtl gll h a mature; 3.2. herelar 4 ce v he seet er ube: .2; s arts to, fire its chara tenstic will be similar;- to that as; shown'as curve 456; of Fig: 1.1;. he u ewillontinue oi e ndsho d associ t d: a ne 4.49: an, ene i d o dition; unti such; im as it, s; xtineuishect, as ii e escribes e inafteri despi he act tha the b 1 s o n er-firin and. t e;- control ri 3 s a a n ased-negatively We have-how observed: the c nditi n o hese..- Bctor=tubeS: andasse i twr hter maenets'durr i g t-h receptionhr hefirst twm mpu sesnthe A? han el. Le us: now: assum ha the: e: ma li e thr impu sesrepr en na heod i al; whi h: may" r: ma ng rw spacin have been received and that the first irnpulseof he odesi halon the BP- chann l; s; now, bei re eived? Unde thisndit n he s th s ribr u 0 tub.e.- 3.124 wiliifiren a nner which; ha be nrre o sly e cr be Rrio z Q- he fin n of he ub h htm rid, 3.95 h -sixth pul e b fit s ia ed esatir rbya. potential lon across. heen entiometerl at point! and which; manhe rac d. th ough t e. movable 

